Hydraulic systems protection levels

If 25 pm is accepted as a general level of protection required for low pressure industrial hydraulic systems, and in the absence of specific requirements from the component manufacturers, the filter ratings given in Table 5.11 are recommended... 

A filter with a bypass housing only provides complete protection for the hydraulic system when the bypass is closed, as in normal use. A non-bypass housing is essential when all the fluid must be filtered all the time. In this case the onset of clogging, cansing an increase in differential pressure to a predetermined level, can trigger a visnal and/or audible alarm, via a pressure switch, or similar device. 

Exposure control Use engineering/technical means, e.g. Low-level filling bowls Suction probes Closed handling systems Soluble packs In-cab electronic sprayer controls Hydraulic boom-folding (These measures should be used in preference to protective clothing)... 

The last two applications, while convenient and initially appealing, require more maintenance and inspection than a simple, ground level monitor. Significant reactive forces can be generated and, therefore, the support structures must be properly engineered. Elevated monitors also require support and hydraulics to be protected by a water spray system if exposed to fires. An elevated monitor is shown in Eigure 7-12. 

The pneumatic or hydraulic controls must also be carefully designed to not only provide the required torque/thrust levels but also to perform their function in the correct time period. This may require the addition of pneumatic boosters or quick exhaust valves. The final element must close fast enough to provide tiie safety protection function but not so fast as to induce excessive and possibly dangerous stresses in the piping due to the system dynamics. 

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